Mistletoebirds are a fascinating example of co-evolution of a bird with parasitic plants. These plants are collectively known as mistletoe. There is a range of species with each having a limited range of host trees. For example some species live on eucalypts, some on acacias, some on melaleuca and so on.
The Australian Mistletoebird feeds almost exclusively on mistletoe berries and has a digestive system modified to deal with the special and limited diet. Apparently, for the first couple of weeks of their lives nestlings are fed exclusively on an insect diet.
The Mistletoebird extracts the berries from an outer protective skin and the soft sweet fruit mass surrounding the hard seed is consumed in the bird’s digestive tract. The seed when voided is sticky and is deliberately wiped by the bird onto its perch. In this way the Mistletoebird spreads new mistletoe plants. So Mistletoebirds and mistletoe plants are dependent on one another.
There are no Mistletoebirds in Tasmania and as far as I am aware no mistletoe plants either which is strong evidence for the codependency of this group of parasitic plants and animal species on the Australian mainland.
I don’t know if mistletoe is spread exclusively by Mistletoebirds, there may be other animal species involved. I have noticed that mistletoe seems to grow strongly along forest margins and other edges. Is this because mistletoe grows best with plenty of light or is it because Mistletoebirds prefer to live along edges?
At Byron Bay I photographed a male Mistletoebird removing the skin of a mistletoe berry. This species of mistletoe was growing on a melaleuca tree.
|This male Mistletoebird is perched in a mistletoe plant on a melaleuca tree. There are two berries just above the bird. Note the strong black bill.|
|The bird has just snapped a berry off from the branch it is perched on.|
|The bird is beginning to squeeze the skin off the berry.|
|The soft inner fruit is starting to emerge from the outer skin.|
|Finally the bird turns the fruit around and grasps the soft inner part which it is after. Shortly after the seed was consumed, a Brown Honeyeater chased the Mistletoebird away.|